Tech Tips

5 reasons to check and replace your chain

Check and replace your bike chain

In the mysterious world of the bike nut you will often hear conversations about chain wear and replacing what's the story?

Did you know bicycle chains are consumables like tires and brake pads?

Here are five pretty good reasons to replace your worn out bicycle chain:


1. Crisper gear changes

One of the first signs of chain wear and stretch are jumping gears. The chain links are no longer aligning with the cassette cogs and the chain just never seems to settle in and behave. If gear adjustment fails to fix this, check your chain wear. 

There are few things worse on a bike than having a chain jumping about on the cassette, especially when putting the power down or climbing.


slug - a slow chain2. Smoother running

A new chain will glide along the cogs on your rear cassette and derailleur pulleys with a sweet hum! Old worn out chains feel sluggish as they have a high slugocity factor. This is to be avoided at all costs.


3. Prevent wear

worn chain ringsOk, so I know my chain is stretched when the gears start slipping and the drivetrain is a bit rough. What is the point of checking chain wear before this happens?

Very noticeable performance issues only really begin when the chain has stretched a lot. The problem is that when you ride a bike with a worn out chain you start doing damage to other drivetrain parts, namely your cassette and even your chainrings.

The stretched chain wears out and can damage the teeth on the cassette. At this stage it is pointless to just replace the chain. A new chain will not mesh smoothly with the old worn-out cassette, so replacement of both will be necessary.

The worst case is riding for so long on a clapped out chain that the front chainring is damaged.

By being vigilant you can use 3-4 chains per cassette and an untold number of chainrings.

EXPERIENCE:  We had a bike brought in for servicing. When a new chain was put on there was daylight shining through the huge gaps between chain and chainring - a result of massive wear from a stretched chain.


kmc bicycle chain4. Reliability

A worn chain may be more susceptible to breaking under load. Riding puts your average chain under all sorts of high loads, particularly mountain biking where the chain may snap and twist around through all sorts of conditions.

This type of wear could lead to the chain weakening and potentially snapping under power. Keeping a healthy chain on your bike can prevent this happening.


5. Save money

As shown in tip 3, leaving chain replacement too long can change a $45 bike shop bill into $150 in the blink of an eye! It is easier and cheaper to buy a new chain than to fork out for chain, cassette and perhaps a chainring plus all the extra labour getting it put on your bike.


Park chain toolHow do I know if my chain is worn in the first place?

Forget about counting miles, chain wear is the result of a blend of mileage, conditions and maintenance. There are two ways to check chain stretch and wear. The first is with a specific chain measuring tool. The second is with a standard metal ruler.

Take a 12" metal ruler (imperial is easiest metric lovers). Line up one end with the exact centre of a chain rivet and check the 12" mark - on a new chain it will line up exactly with the centre of the rivet 12 complete links away.

measure chain links to check wearOn a used chain there will be some stretch. If this is less than 1/16" (1.6mm) the chain is still fine to use, keep riding but keep checking frequently. If the chain growth is greater than 1/16" (1.6mm) it is probably time to think about replacing. If your chain has stretched to 1/8" (3.2mm) then the damage has been done. See tip 3.

TIP!  These are very fine measurements and require care and a good eye, which is why chain measuring tools are useful. When using a ruler, keep in mind that the outer edge of the rivet is almost 2mm away from the centre. When the 12" mark on your ruler lines up with this, it's time to replace your chain.



ProfileAuthor: Christian Woodcock
Christian loves riding bikes. He has many years experience working in bike shops and has raced mountain bikes at a high level with success. These days expect to see him climbing and suffering on a road bike, or talking it up on the trails with mates.

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